Overload-release-type line post insulator

ABSTRACT

An overload-release-type line post insulator comprises an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to an insulator-holding structure either directly or indirectly through a support insulator, which bolt allows the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.

Unite States Patent [72] Inventors Tsuneaki Shimizu Chita-gun; Kazunao Ueno, Nagoya, both of Japan [21] App]. No. 85,531 [22] Filed Oct. 30, 1970 [45] Patented Jan. 11, 1972 [73] Assignee NGK Insulators, Ltd.

Nagoya, Japan [32] Priority Feb. 25, 1970 [33] Japan [31 45/ 17891 [5 4] OVERLOAD-RELEASE-TYPE LINE POST INSULATOR 12 Claims, 4 Drawing Figs.

[52] U.S.Cl 174/158 R, 174/161 R, 248/64, 248/65 [51] lnt.Cl ..H0lb 17/16 [50] Field of Search 174/40 R,

40 TD, 43,45 R, 45 TD, 148, ,158 R, 161 R; 248/65, 64,221

Primary Examiner- Laramie E. Askin Att0rneys-Robert E. Burns and Emmanuel J. Lobato ABSTRACT: An overload-release-type line post insulator comprises an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to an insulator-holding structure either directly or indirectly through a support insulator, which bolt allows the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximityvof the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and theswinging of the insulating body about the hinge bolt.

PATENIED JAN] 1 I972 SHKET 1 UF 2 PAH-INIEBJAM 1 I972 I 4 35 50 sum 2 OF 2 Fig. 3

Fig. 4

. (melon ART) OVERLOAD-RELEASE-TYPE LINE POST INSULATOR This invention relates to an overload-release-type line post insulator, and more particularly to an overload-release-type line post insulator supporting a transmission line conductor whose insulating body is protected from breakage caused by an excessively large static or dynamic overload applied to the line conductor by an emergency accident, such as conductor breaking, galloping of the transmission line, and collision of an unexpected matter to a transmission line supporting structure.

A conventional line post insulator, which includes an insulating body and a metallic cap fixed to the insulating body, is rigidly mounted on a supporting structure by directly securing its metallic base to such structure. Accordingly, when an excessively large overload is applied to a line conductor held by a clampcarried by a metallic cap secured to the head portion of the conventional line post insulator, a large bending moment is caused at the base portion thereof. As a result, the insulating body of the line post insulator is sometimes broken to cause a conductor drop fault. When one of a series of line post insulators on adjacent structures of a transmission line is broken in such a manner, there is a risk that the insulator breakage might propagate to the insulators of adjacent structure step by step. If such propagation of the insulator breakage should be caused, it may lead to a large fault.

According to the present invention, there is provided an improved overload-release-type line post insulator, which is based on the finding of the inventor that an overload applied from a line conductor to the insulating body of a line post insulator can be absorbed by the breakage of one or more locking pins and the swinging of the insulating body per se about a hinge bolt, the hinge bolt swingably connecting a metallic base of the line post insulator to a mounting base secured to an insulator-holding structure, e.g., a tower, which locking pin or pins are disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging.

The invention will be more fully understood by reference to the following detail specification and claims taken in connection with the appended drawings, in which:

FIG. 1 is a plan view of a line post insulator assembly, using a line post insulator according to the present invention;

FIG. 2 is a side view of the line post insulator assembly;

FIG. 3 is a side view of an embodiment of the present invention, which is difi'erent from the line post insulator assembly of FIG. 1; and

FIG. 4 is a side view of a typical known line post insulator assembly.

Like parts are designated by like numerals and symbols throughout the drawings.

Referring to FIGS. 1 and 2, the insulating body 1 of a line post insulator according to the present invention has a metallic base a secured to the earth side end thereof and a metallic cap 4 secured to the top portion thereof, which metallic cap 4 provides a clamp 3 for holding a transmission line conductor 2. A mounting base c having a hinge portion b, with an opening extending in the longitudinal direction of the conductor 2, is fixed to a tower structure 5. The metallic base a of the line post insulator is connected to the hinge portion b of the mounting base c by means of a hinge bolt d, in such a manner that the insulating body 1 of the line post insulator can swing about the hinge bolt d in the longitudinal direction of the conductor 2. One or more of locking pin or pins e are disposed in the proximity of the hinge bolt :1 in such a fashion that the locking pin or pins e normally prevent the insulating body from swinging or rotating about the hinge bolt d, but upon application of an overload to the insulating body, the pin or pins act to release the overload.

According to the invention, it is also possible to secure the mounting base to the tower structure 5 after the line post insulator is connected to the mounting base 0 in the aforesaid manner.

The one or more locking pin or pins e are so designed as to be broken at a rated longitudinal cantilever load, by properly selecting the dimensions and the dispositions thereof; namely, the material and the diameter of each pin, the number of the pins, the layout of the pin or pinscThe aforesaid rated longitudinal cantilever load at which the locking pin or pins e are broken should be lower than the cantilever-breaking strength of the insulating body 1 of the line post insulator.

With an insulator assembly inclusive of the overload release-type line post insulator of the aforesaid construction according to the invention, the normal load on the line post insulator is not sufficiently large forbreaking the locking pin or pins e, so that the locking pin or pins e act to prevent the insulating body 1 of the line post insulator from swinging about the hinge bolt d. On the other hand, when an overload is applied to the line post insulator, for instance, by an unbalanced loading on the conductor 2 on opposite sides of the line post insulator, then the overload generates such shearing energy which acts to break down the locking pin or pins e. Whereby, the insulating body 1 of the line post insulator is freed from the restriction of the locking pin or pins e and begins to swing about the hinge bolt d for absorbing the overload energy. Thus, the insulating body 1 of the line post insulator is protected from the breakage due to such overload. It should be noted here that the breakdown of the locking pin or pins 2 itself acts to absorb the overload energy for materially reducing the risk of the breakage of the line post insulator.

FIG. 3 illustrates another line post insulator according to the present invention. In this embodiment, a metallic base a secured to an insulating body 1 is indirectly connected to a mounting base a secured to a tower structure 5, by inserting an adapter f therebetween. The adapter f is secured to the metallic base a by suitable means, e.g., by bolting, and a hinge portion h integrally formed with the adapter f is pivotally connected to an eye portion g integral-withthe mounting base 0, by means of a hinge bolt d and at least one locking pin e, as shown in the figure. The line post insulator of the invention thus mounted on the tower structure 5 is normally prevented from swinging about the hinge bolt d by the presence of the locking pin or pins e, but upon application of an overload, the pin or pins e are broken and the line post insulator swings about the hinge bolt d for absorbing the energy of the overload. Accordingly, the line post insulator is protected from breakage by the application of the overload.

FIG. 4 shows a typical known line post insulator. A metallic base a of the known line post insulator is rigidly connected to a tower structure 5, and the line post insulator is not movable relative to the tower structure 5. Accordingly, any overload from conductor 2 is fully applied to the line post insulator, especially to an insulating body 1 at the proximity of the metallic base a, for causing the line post insulator to break.

It is apparent from the comparison of the known line post insulator of FIG. 4 with the line post insulator of the invention, as shown in FIG. 3, that an overload-release-type line post insulator can be provided by using a fairly simple structural modification, which includes the addition of an adapter f having a hinge portion h to be connected to an eye portion g of the mounting base 0 by a hinge bolt d and one or more locking pin or pins e As can be seen from the comparison of FIGS. 1 and 3, the hinge portion b or 11 can be provided on either of the mounting base c or the adapter f secured to the metallic base :1. Accordingly, the coating eye portion, such as the eye portion g of FIG. 3, can be provided on either of the metallic base a and the mounting base c, so as to be connected to the aforesaid hinge portion b or h by a hinge bolt d and at least one locking pin 2. In short, the disposition of the hinge portion and the coacting eye portion is not restricted to either one of those as shown in FIGS. 1 and 3.

Any number of the locking pin or pins 2 can be used, as long as they are disposed in the proximity of the hinge bolt d without departing from the scope of the invention. It has been found, however, that preferable results can be achieved by using only one locking pin 2 disposed in parallel with the hinge bolt d.

The present invention is particularly suitable for application to line post insulators which are horizontally mounted, but the invention is not restricted to such application alone.

Although the present invention has been described by referring to an embodiment connected to a tower, the use of the line post insulator of the invention is not limited to those connected to the tower but it can be connected to any member, such as metallic fixtures and other cooperating insulators. It is possible to construct a line post insulator assembly consisting of two or more line post insulators, of which one or more line post insulators are of the type according to the present invention. In short, the present invention is not restricted by the place of its application.

Furthermore, it is an important feature of the invention that the locking pins e can easily be replaced when they are broken.

Thus, the present invention contributes greatly to the industry by improving the reliability of the electric power transmission.

What is claimed is:

1. An overload-release-type line post insulator, comprising an insulating body, a metallic cap secured to the free end of the insulating body and a clamp for holding a line conductor secured to said metallic cap, a metallic base secured to the other end of the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.

2. An overload-release-type line post insulator according to claim 1, wherein the insulator provides only one locking pin disposed in parallel with the hinge bolt.

3. An overload-release-type horizontal mounting line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.

4. An overload-release-type horizontal mounting line post insulator according to claim 3, wherein the insulator provides only one locking pin disposed in parallel with the hinge bolt.

5. An overload-release-type line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to a support insulator held by an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.

6. An overload-release-type line post insulator according to claim 5, wherein the insulator provides only one locking pin disposed in parallel with the hinge bolt.

7. An overloadrelease-type horizontal mounting line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to a support insulator held by an insulator-holding structure, said bolt being allowable for the insulatin body to swing along the longitudinal direction of the line con uctor, and at east one locking pm disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt. 7

8. An overload-release-type horizontal mounting line post insulator according to claim 7, wherein the insulator includes only one locking pin disposed in parallel with the hinge bolt.

9. An overload-release-type line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, an adapter secured to the metallic base, a hinge bolt for swingably connecting said adapter to a mounting base fixed to an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.

10. An overload-release-type line post insulator according to claim 9, wherein the insulator includes only one locking pin disposed in parallel with the hinge bolt.

11. An overload-release-type horizontal mounting line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, an adapter secured to the metallic base, a hinge bolt for swingably connecting said adapter to a mounting base fixed to an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of'the insulating body about the hinge bolt.

12. An overload-release-type horizontal mounting line post insulator according to claim 11, wherein the insulator provides only one locking pin disposed in parallel with the hinge bolt. 

1. An overload-release-type line post insulator, comprising an insulating body, a metallic cap secured to the free end of the insulating body and a clamp for holding a line conductor secured to said metallic cap, a metallic base secured to the other end of the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating boDy is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.
 2. An overload-release-type line post insulator according to claim 1, wherein the insulator provides only one locking pin disposed in parallel with the hinge bolt.
 3. An overload-release-type horizontal mounting line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.
 4. An overload-release-type horizontal mounting line post insulator according to claim 3, wherein the insulator provides only one locking pin disposed in parallel with the hinge bolt.
 5. An overload-release-type line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to a support insulator held by an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.
 6. An overload-release-type line post insulator according to claim 5, wherein the insulator provides only one locking pin disposed in parallel with the hinge bolt.
 7. An overload-release-type horizontal mounting line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, a hinge bolt for swingably connecting said metallic base to a mounting base fixed to a support insulator held by an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.
 8. An overload-release-type horizontal mounting line post insulator according to claim 7, wherein the insulator includes only one locking pin disposed in parallel with the hinge bolt.
 9. An overload-release-type line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, an adapter secured to the metallic base, a hinge bolt for swingably connecting said adapter to a mounting base fixed to an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.
 10. An overload-release-Type line post insulator according to claim 9, wherein the insulator includes only one locking pin disposed in parallel with the hinge bolt.
 11. An overload-release-type horizontal mounting line post insulator, comprising an insulating body, a metallic cap secured to the insulating body and having a clamp for holding a line conductor, a metallic base secured to the insulating body, an adapter secured to the metallic base, a hinge bolt for swingably connecting said adapter to a mounting base fixed to an insulator-holding structure, said bolt being allowable for the insulating body to swing along the longitudinal direction of the line conductor, and at least one locking pin disposed in the proximity of the hinge bolt for normally preventing the insulating body from swinging, whereby an overload from the line conductor to the insulating body is absorbed by the breakage of the locking pin and the swinging of the insulating body about the hinge bolt.
 12. An overload-release-type horizontal mounting line post insulator according to claim 11, wherein the insulator provides only one locking pin disposed in parallel with the hinge bolt. 